Physical and Chemical Diversity of Star-Forming Regions and Its Propagation to Protoplanetary Disks

最近，人们认识到低质量的0级源具有显著的化学多样性。在本研究中，我们重点研究了一个在原恒星附近的温热区域显示出异常丰富的碳链分子的极端情况（Warm carbon-chain Chemistry； WCCC），并对其起源和向I类阶段的演化进行了观测研究。以下是主要成果。首先，我们在WCCC源IRAS15398-3359附近新发现了一个富含碳链分子的年轻无星核心Lupus-1A。另一个WCCC源L1527也位于类似的年轻无星核心TMC-1附近。这一结果进一步支持了我们关于WCCC起源于母核快速收缩的假设。其次，我们用PdBI研究了L1527中碳链分子的高分辨率分布。碳链分子的紧凑分布支持由CH_4在原恒星附近蒸发引发的WCCC机制。更重要的是，碳链分子被发现甚至存在于落入原恒星的气体中，这表明碳链分子将被带入原行星盘。我们搜索了WCCC活动的1类源，并且确实在L1527附近找到了这样一个例子。在这项研究中，我们获得了关于WCCC源如何向原行星盘演化的新信息。

Recently, it is recognized that the low-mass Class 0 sources shows significant chemical diversity. In this study, we have focused on one extreme case showing extraordinary richness of carbon-chain molecules in a lukewarm region near the protostar (Warm Carbon-Chain Chemistry ; WCCC), and have observationally studied its origin and its evolution toward the Class I stage. The followings are major outcomes. First, we have newly found a young starless core with rich carbon-chain molecules, Lupus-1A, near the WCCC source IRAS15398-3359. The other WCCC source, L1527, is also located near the similar young starless core TMC-1. This result further supports our scenario that the WCCC originates from fast contraction of the parent core. Second, we have studied high-resolution distributions of carbon-chain molecules in L1527 with PdBI. Compact distributions of carbon-chain molecules support the WCCC mechanism triggered by the evaporation of CH_4 near the protostar. More importantly, carbon-chain molecules are found to reside even in the gas infalling to the protostar, suggesting that carbon-chain molecules will be brought into protoplanetary disks. We have searched for the Class 1 sources with the WCCC activities, and have indeed found such an example near L1527. In this study, we have obtained novel information on how the WCCC sources will be evolved toward protoplanetary disks.